®
Basic Calorimetry Set
3
Experiment 1: What is a Calorie?
Equipment Needed
• Calorimeters, 2 pieces
• Thermometer
• Balance
• Hot and cold water
Introduction
When two systems or objects of different temperature come into contact, energy in the
form of heat is transferred from the warmer system into the cooler. This transfer of heat
raises the temperature of the cooler system and lowers the temperature of the warmer sys-
tem. Eventually the two systems reach some common, intermediate temperature, and the
heat transfer stops.
The standard unit for measuring heat transfer is the calorie. A calorie is defined as the
amount of energy required to raise the temperature of one gram of water from 14.5° C to
15.5° C. However, for our purposes, we can generalize this definition by simply saying
that a calorie is the amount of energy required to raise the temperature of one gram of
water one degree Celsius (the variation with temperature is slight).
In this experiment, you will combine hot and cold water of known temperature and mass.
Using the definition of the calorie, you will be able to determine the amount of heat energy
that is transferred in bringing the hot and cold water to their final common temperature,
and thereby determine if heat energy is conserved in this process.
Procedure
1. Determine the mass of the empty calorimeter, M
cal
. Record your result in Table 1.1.
2. Fill the calorimeter about 1/3 full with cold water. Measure the mass of the calorime-
ter and water together to determine M
cal + water cold
. Record your result.
3. Fill a second calorimeter approximately 1/3 full of hot water. The water should be at
least 20° C above room temperature. Weigh the calorimeter and water together to
determine M
cal + water hot
. Record your result
4. Measure T
hot
and T
cold
, the temperatures the hot and cold water, and record your
results.
5. Immediately after measuring the temperatures, add the hot water to the cold water and
stir with the thermometer until the temperature stabilizes. Record the final tempera-
ture of the mixture, T
final
.
6. Measure the final mass of the calorimeter and mixed water, M
final
.
7. Repeat the procedure twice with different masses of water at different temperatures.
(You might try adding cold water to hot instead of hot to cold.)
(15 pages)
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